1. Field of the Invention
The invention relates to polymers and their use, in particular, for surface-sizing of paper or paper-like materials.
2. Description of Related Art
A whole series of very effective anionic surface-sizing agents for paper which are employed not only as aqueous solutions but also in the form of aqueous emulsions have hitherto already been in use. Most of the hitherto known products have a strongly anionic character and are therefore limited to a certain degree in their range of application. To develop their full sizing effect, they require the presence of Al ions in the crude paper, that is, they can be used primarily for those types of paper which are prepared at acidic pH values. Examples of paper of these types are alum-containing or presized papers usually containing clay as a filler. However, it is a disadvantage that on alum-free and chalk-containing papers they exhibit only little or even in many cases no sizing at all. Since in recent years a trend towards production under neutral conditions, using chalk as filler, has been observed in paper production, it is important nowadays that a paper-sizing agent can be used for all customary types of paper and also shows a uni-formly good sizing effect for all those types. A surface sizing agent for paper which covers all possible production conditions under which paper is produced nowadays, would therefore be of very great interest not only for industry but also in terms of economics.
It would therefore be desirable to prepare a sizing agent which can be used not only in the acidic pH range in the case of alum-containing and presized papers but also in the neutral to weakly alkaline pH range in the case of alum-free and chalk-containing papers. In addition, the use of such a sizing agent should also give good results in the sizing of wood-containing papers.